The present disclosure relates to a display device which displays images by using an organic electroluminescence element, and particularly to a display device having a touch sensor function.
In recent years, there are more and more display devices and electronic units having a touch sensor function which allows users to input information (detect objects) with their fingers, styluses, or the like. Concern over such display devices and electronic units is that the entire thickness of the device is increased because a touch panel is often incorporated in the device as a module by being mounted directly on a display screen, for example.
To address this, the following technique is being proposed in liquid crystal displays (LCDs) having a touch sensor function. In a liquid crystal display, an image is displayed in such a manner that a voltage is applied to a liquid crystal layer sandwiched between a pixel electrode and a common electrode. By using this common electrode for image display also as a driving electrode for sensor, the thickness of the entire device is reduced (for example, see Japanese Unexamined Patent Application Publication No. 2009-244958). In this case, a common signal to be applied to the common electrode to drive display is used as a driving signal for sensor. In order to detect an object, a touch panel utilizes both of a driving electrode and a sensing electrode which form a capacitance. However, allowing an existing electrode (such as common electrode) in a display device to serve also as the driving electrode makes it possible to additionally provide only the sensing electrode.